The long-term goal of this proposal is to understand the mechanisms by which oxidative stress contributes to seizure-induced neuronal death. Neuronal death is a major devastating consequence of status epilepticus. The mechanisms of seizure-induced brain damage remain obscure. Understanding these mechanisms in molecular terms may providenovel therapeutic approaches aimed at preventing seizure-induced neuronal death. Work in this laboratory has demonstrated that seizure activity results in increased mitochondrial superoxide (CV) production. The goal of this proposal is to determine mechanism by which mitochondrial O2~ mediates seizure-induced neuronal death. It is hypothesized that seizure-induced neuronal injury results in part from oxidative inactivation of mitochondrial, aconitase. One important mechanism of O2~toxicity is based on its direct oxidation and resultant inactivation of iron- sulfur (Fe-S) proteins such as aconitases and thereby act as a precursor of more potent oxidants e.g. hydroxyl radical. Additionally, the role of mitochondrial aconitase in the tricarboxylic acid cycle can have a major impact on mitochondrial bioenergetics and metabolism. Seizure-induced posttranslational inactivationof mitochondrialaconitase is predicted to contribute to altered mitochondrial iron homeostasis, increased free radical burden and/or a bioenergetic deficit. Specific aim 1 will determine the consequences of seizure-induced oxidative inactivation of mitochondrial aconitase. Specific aim 2 will examine if mitochondrial aconitase inactivation and consequent release of iron and hydrogen peroxide imposes a free radical burden and neurotoxicity. Specific aim 3 will determine if modulation mitochondrial O2~with catalytic antioxidants and superoxide dismutase-2 influences seizure-induced neuronal death. Whole animal studies will be combined with a diversity of tools and techniques that include high performance liquid chromatography, mass spectrometry, confocal microscopy and transgenic/knockout mice. These studies can identify the precise oxidative events initiated by prolonged seizure activity and suggest novel therapeutic strategies for rescuing neurons in the context of status epilepticus in humans.